The present invention relates to a coil unit relating to non-contact power transmission using a coil, a method of manufacturing the same, an electronic instrument, and the like.
Non-contact power transmission has been known which utilizes electromagnetic induction to enable power transmission without metal-to-metal contact. As application examples of non-contact power transmission, charging a portable telephone, a household appliance (e.g., telephone handset), and the like has been proposed.
Non-contact power transmission has a problem in that a transmission coil produces heat. Technologies which suppress such heat generation have been proposed. JP-A-8-103028 discloses a design method which suppresses heat generation during non-contact charging. JP-A-8-148360 discloses technology which suppresses heat generation by adapting a suitable configuration of a coil and a magnetic material. JP-A-11-98705 discloses a non-contact charging device provided with an air-cooling mechanism. JP-A-2003-272938 discloses a structure in which a ceramic is disposed between a primary coil and a secondary coil to dissipate heat. JP-A-2005-110357 discloses the structure of a housing with an improved heat dissipation capability.
Non-contact power transmission transmits power between coils utilizing a magnetic field. Therefore, when a metal is brought close to the magnetic field, the magnetic field is absorbed by the metal, whereby a decrease in efficiency or induction heating of the metal occurs. This makes it difficult to utilize a metal optimum for heat dissipation.
Some aspects of the invention may provide a coil unit which exhibits an excellent heat dissipation capability, a method of manufacturing the same, and an electronic instrument.